A scalabe solution to connect ip-based BSS to legacy GSM networks

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Dmitri Soloviev dmi3sol at gmail.com
Mon Mar 25 09:34:29 UTC 2013


This is just a proposal how a scalable cost-effective solution can look
like. It is not implemented yet, but the goal is to work out a right
approach.
I developed quite similar things in 2003, when I interfaced ip.access BSC
to S-12 and AXE-10.

This is a piece of operator infrastructure, desired to be sold to MNO. In
Russia it also assumes certification procedure, held by authorized center.

On Mon, Mar 25, 2013 at 1:16 PM, John Wu <jwjohn0 at gmail.com> wrote:

> Hi Dmitri,
> Have you developed the solution connect private GSM network to operator
> core network?
> But this should be allowed by the local operator, right?
>
>
> On Sat, Mar 23, 2013 at 5:09 PM, Dmitri Soloviev <dmi3sol at gmail.com>wrote:
>
>> Hi
>>
>> we've got several requests to extend existing GSM networks with our radio
>> equipment, where ip transport is appreciated.
>>
>> Please take a look at my vision of interfacing A-over-ip to a legacy GSM
>> A-interface.
>>
>> Building blocks:
>>
>> 1. OpenBSC with ip.access-compatible A-over-ip interface
>>
>> 2. MGCP-controlled transcoder, built with Sangoma D-series cards. Can be
>> assumed as a shared resource, available for several BSC instances.
>> http://www.sangoma.com/assets/docs/datasheets/en/d500.pdf
>>
>> 3. TelscaleSS7card - a stand-alone signaling and media gateway, with 2 E1
>> and 2 Ethernet interfaces, running embedded linux on board.
>> It converts A-over-ip to A-interface, acts as MGCP call agent for BTSs,
>> transcoders and other telscaleSS7cards. A card is implemented in PCI form
>> factor, but bus is used just to provide power supply.
>> In other words, a card can act either as a combined SG+MG, converting
>> A-over-ip into SS7 and RTP into E1 timeslot, or just a MG, converting RTP
>> into E1, without any impact on the host system.
>>
>>
>> When a [signaling gateway + call agent] detects ASSIGNMENT_REQUEST or
>> HANDOVER_REQUEST, it stores cic value. As soon as ASSIGNMENT_COMPLETE or
>> HO_REQ_ACK is detected, it builds RTP chain that unites
>> BTS<->transcoder<->media_gateway. The chain is broken after the call is
>> finished.
>>
>> Depending on the chosen cross plane, 4U 19" industrial PC can carry
>> several BSC instances with transcoding, serving about 20 E1 interfaces (ea
>> about 80 ARFCNs). Performance requirements for industrial PC cards are also
>> negligible: computer will run OpenBSC and configure transcoder cards, being
>> controlled by means of MGCP.
>>
>>
>>
>> Best Regards,
>> Dmitri
>>
>
>
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